1. Field of the Invention
The present invention relates to natural lighting systems for roofs, and more particularly, to a light transmitting panel connectable within a metal roofing system.
2. Description of the Related Art
For many years commercial buildings have utilized sheet metal roofs. Recently it has become more common and popular to utilize sheet metal roofs on residential homes, shops, patios and the like. Typically, the standing seam metal roof utilizes metal sheets having lateral upturned edges. The panels are laid side by side with the lateral edges of one panel contiguous with the upstanding edge of adjacent panels. The panels are joined together by a cap piece or by folding over the upstanding edge to tightly hold the panels together. The roofs are sloped so that water runs down the trough formed between the upstanding edges of each panel.
The above referenced roofing systems may take many forms such as, but not limited to, trapezoidal, 90-degree modular, architectural, and industrial. Metal roofs may have minor ribs, stiffener ribs, or no ribs of all and may be a screw down roofing system. All of these roofing systems are similar in the requirement of attaching the panels at adjacent edges or side rails.
It is very often desirable with metal roofing systems to have additional natural lighting whereby sunlight is permitted to enter the structure through the roof. Heretofore, this natural lighting was provided by installing domed skylights of either the curb or curbless variety. Unfortunately, skylights can be expensive and create water leakage. One of the causes of water leakage is due to the restricted flow path of water between the domed skylight and the standing seam, whereby the water level rises such as to penetrate the roof at the panel junctions. Additional problems arise with domed skylights when freezing temperatures are encountered. Ice and/or snow may collect between the skylight and the dome, and as the ice melts it is blocked by ice dams resulting in the level of water rising and penetrating the panel seam.
Curbed skylights include a “curb” which is a raised structure formed around the opening in the roof upon which the transparent material is attached. The curb raises the seal between the curb and the transparent material above the point of water flowing down the roof. However, curbs are expensive to construct and to install. If not installed correctly leaks will develop around the curb and roof junction resulting in expensive repair. Additionally, installing curbed skylights requires cutting a hole in the existing roof which is performed at the job site increasing the cost of the skylight.
Curbless skylights have been utilized and by definition do not require a raised frame. However, the prior art skylights typically utilize flashing, mechanical fasteners, and or sealing rings to install and to alleviate water leakage. Although curbless skylights do provide benefits over curbed skylights they often increase the weight of the panel with framing, increase the likelihood of water leakage and increase the cost of the metal roofing.
In addition, OSHA requires that skylights be less than twelve inches square or metal grate is required to be placed over the skylight. This so called OSHA 252 bag test is instituted to prevent people, in particular, workers from falling through the skylight when it is stepped or sat on. In order to meet these requirements the skylights and light transmitting panels in the prior art required a combination of fasteners, clips, clips, and fasteners, flanges, etc. in order to secure the transparent or semi-transparent material to the sheet metal surfaces. The differences in the respective linear coefficients of expansion of the various materials of construction resulted in systems that would inherently fail over time. The failures resulted from movement of the various materials in various directions due to the heating and cooling affect that occurs every day. With materials often moving in opposite directions fatigue occurs causing cracks, leaks and the inability to meet OSHA and UL testing requirements as discussed below.
During the heating and cooling cycle of a typical day, the metal roof and its components expand and contract. For example, it is not an unusual occurrence in a normal pitched roof to expand and contract as much as 6″ over a 100 linear feet. As a result of this and other effects, UL 90 requires that a panel withstand a 90 mph wind created uplift without loss of containment. In order to achieve this, again the prior art systems employed very elaborate clip and/or conventional fasteners. However, due to the vastly different linear expansion coefficients of the fasteners, metal panels, clips, and metal panels and light transmitting panels, loss of containment or component failure would occur as noted above over time.
It would be a benefit therefor, to have a light transmitting panel adapted for connection in a metal roofing system that did not comprise the use of clips, fasteners and the like to secure the light transmitting panel to the metal panel while at the same time meeting OSHA 252 bag test and UL 90 requirements. It would be a further benefit to have a light transmitting panel which has side rails adapted for connecting with metal roofing panels. It would be a still further benefit to have a light transmitting panel prefabricated for installation on site in a metal roofing system in the same manner as standard metal roofing panels. It would be a still further benefit to have a light transmitting panel having substantially the same strength characteristics as adjacent metal panels.